A mutation that changes the tryptophan codons in region 1 of the leader peptide into codons for alanine?
A)Transcription of the structural genes will proceed only when
alanine levels are low
B)Transcription of the structural genes will proceed only when
alanine levels are high
Answer :
1. The tryptophan codons are needed in region 1, because this makes the ribosome pause so 2 and 3 can bind.
If they now code for alanine, the ribosome wouldn't pause, 1&2 would bind and 3 & 4 would bind causing attenuation.
A)Transcription of the structural genes will proceed onlywhen alanine levels are low.
If alanine codons have replaced tryptophan codons, then under conditions of high alanine, the stalling of the ribosome will not occur. The attenuator will form, stopping transcription. The ribosome will stall when alanine is low, so transcription of the structural genes will occur only when alanine is low.
Get Answers For Free
Most questions answered within 1 hours.